The invention relates to novel protective coatings for metal objects, and more particularly, to novel coating compositions for protecting metal objects from corrosion and/or other degradation during storage prior to the contemplated usage. Since the invention is primarily directed to metal pipes, it wil be described hereinafter for purposes of illustration by reference thereto.
Metal pipes such as those contemplated for inground implantation require an anti-corrosion protective system. Typically, such a system consists essentially of a rubber-based primer coating over which a rubber-based, pressure-sensitive adhesive tape is spirally wound. Such an anti-corrosion system is generally referred to in the art as pipewrap.
In the art of laying pipeline, whether in ground or above ground, the pipes generally lie in storage for a period of time, which may be as much as a year or more, prior to application of the pipewrap or other protective system. This storage may, for example, be outdoors at the time of manufacture, at the site of use, or a combination of both.
During the time of storage, it will be appreciated that the pipes also require protections from degradative forces, which protection need not be as long-lasting as the protective system ultimately applied, i.e. it need only serve its protective function for the time in storage.
In general, storage coatings currently available have a protective life on the order of six months. However, pipes delivered to the field frequently remain in storage for considerably longer periods of time, say, for example, a year or more.
The task of this invention, therefore, is to provide a storage coating for metal objects, particularly pipes or the like, which will provide protection for extended periods of time and which preferably are characterized as being easy to apply, dry quickly to a substantially tack-free condition and, if not completely removed prior to use, are compatible with the protective coating which will ultimately be placed thereover.